Abstract: In order to study the effect of microwave calcination on the morphology and properties of powders, the barium titanate nano-powders was synthesized via a hydrothermal reaction under atmospheric pressure at 80 ℃ for 2 h with BaCl₂ and TiCl₄ as the raw materials and NaOH as mineralizer. The physical properties of the materials under different calcination conditions were characterized and analyzed by XRD, FT-IR, XPS, SEM, BET and EDS. The experimental results show that the BaTiO₃ nano-powders synthesized by hydrothermal method under atmospheric pressure is cubic phase and the optimum calcination method is microwave calcining at 700 ℃ for 0.5 h with high crystallinity, complete crystalline form, low weight loss rate of only 1.1%, average particle size of 39 nm, specific surface area of 25.975 m²/g and barium-titanium ratio of 1.001 7. These results demonstrate that microwave calcination can benefit to prepare the barium titanate nano-powders with small particle size, good dispersion and uniformity.